1. Field of the Invention
The present invention relates to a sputtering power-supply unit for use in a sputtering device for the manufacture of a compact disc (CD) or a digital versatile disk (DVD).
2. Description of the Related Art
A sputtering power-supply unit for use in a sputtering device for the manufacture of a compact disc (CD) or a digital versatile disk (DVD) is known in Japanese Patent No. 2835322, Japanese Patent No. 2835323 and U.S. Pat. No. 5,576,939.
Formation of a film on the compact disc or the digital versatile disk is carried out by a magnetron sputtering technology. If suppression of arc discharge fails during this sputtering, a target material is scattered to adhere to the disk, with the result that production yield is reduced. Accordingly, if arc discharge occurs during the sputtering, a reverse voltage is generated to suppress the occurrence of the arc discharge. However, an arc suppression circuit has been destroyed sometimes because of disconnection of an output cable or the like.
Furthermore, in order to complete the film formation on the disk within a short time, it is necessary to increase the average power output from the sputtering power-supply unit.
However, when the average power is increased, arc discharge easily occurs during the sputtering, increasing the number of times when the suppression of the arc discharge fails.
It is desired that even if such arc discharge occurs, fluctuation in the sputtering current is reduced to stably continue sputtering discharge.